In Zimbabwe, poachers for the first time are poisoning watering holes to snare tusks from elephants.

In South Africa, a Thai national allegedly evaded rhino hunting quotas by using Thai sex workers as fake hunters. And 13 safari operators, veterinarians and even a pilot are to appear in court next week, accused of poaching rhinos and trying to smuggle out their horns.

The cases show how the skyrocketing price in Asia for tusks, horns and other wildlife parts is undermining increased efforts to crack down on smuggling. The parts are used for alleged medicinal properties or, in the case of ivory, for artwork.

Elephant tusks and rhino horns have doubled in price on the black market from just a few years ago. Poachers can get around $1,800 a kilo (2.2 pounds) for tusks and $10,000 a kilo for rhino horns.

"Asian and African governments must work together to disrupt trade chains and to bring wildlife criminals to justice," said Morne du Plessis, who heads the WWF chapter in South Africa. "Demand for rhino horn and elephant ivory is threatening to destroy a large part of Africa’s natural heritage."

Zimbabwe's wildlife agency reported Tuesday that nine elephants and at least five lions died from poisoning at watering holes in recent weeks.

The elephants' ivory tusks were removed but the lions' heads and skins were left intact, said agency spokeswoman Caroline Washaya-Moyo, suggesting that the lions were accidental victims of the crime.

Buffalo were also killed, as were vultures that preyed on the dead animals.

The conservation group Born Free estimates that 35,000 elephants are killed each year for their ivory across Africa, some 15 percent of the total population.

In South Africa, a Thai businessman is accused of violating rhino hunting quotas by using Thai sex workers to pose as hunters in photos with dead rhinos. The allegation is that the women never even fired a weapon and were used to evade South Africa's cap of one rhino a year per hunter.

The suspect, Chumlong Lemtongthai, allegedly paid nearly $10,000 per kilo (2.2 pounds) of rhino horn and sold them on the black market for $55,000 a kilo.

While his trial is pending, 13 South Africans will be formally charged on Sept. 30 with buying hundreds of rhinos at auctions, then slaughtering them to illegally sell the horns in Asia.

Dubbed the "Groenewald Gang" after Dawie Groenewald, owner of Out of Africa Adventurous Safaris, the defendants include his wife, two vets and a helicopter pilot.

The carcasses of 20 rhinos were found on Groenewald's property with their horns cut off. The defendants are expected to enter guilty or not guilty pleas at their arraignment.

"The Groenewald Gang has challenged the conventional wisdom of what a poacher is," says Matt Lewis, who heads WWF's African species program. "This is not a desperate and impoverished villager taking up a gun and going off to shoot someone else’s animal in order to get a few dollars to feed his family. This group orchestrated a plan to profit from the exploitation of rhinos in a systematic way, while appearing to be involved in the conservation of that species. Very devious, very crass and driven purely by greed."

Last month, South Africa's government said it might stop rhino trophy hunting due to the abuse by some parties. And Britain and the U.S. are sponsoring a workshop in South Africa next week on strategies for attacking the problem.

Already this year, 165 arrests have been made and 287 rhinos were illegally killed in South Africa alone. At that pace, 2011 will top 2010, when 333 rhinos were poached.

Some 25,000 rhinos are estimated across all of Africa, an improvement from 2007 when there were 22,000, but experts worry that trend could soon shift.